I sprung a leak the other day in supply line to my heater. I cut out all the old and got all the new stuff in, but after trying for about two hours my dad and I could not get the union nut onto the fitting after about an hour of trying. We tried the old nut to see if maybe we got the wrong type, but the old nut won't go on either. It feels like the threads aren't matching up; they start to grab but then it pushed itself off. Has anyone else run into something like this before? The company that opened the pool got them on somehow, so I'm either going to call them or bypass the heater for now. It's just a little frustrating because it's something that looks so simple.